U.S. patent number 8,132,887 [Application Number 12/660,634] was granted by the patent office on 2012-03-13 for universal closed loop color control.
This patent grant is currently assigned to Innolutions, Inc.. Invention is credited to Michael Friedman, Manojkumar Patel, Piyushkumar Patel.
United States Patent |
8,132,887 |
Friedman , et al. |
March 13, 2012 |
Universal closed loop color control
Abstract
A system and processes for the accurate measurement and control
of image color values on a printing press with or without the
presence of a color bar. More particularly, a universal closed loop
color control system and processes for controlling the color
quality of color images printed on a substrate online or offline,
with or without a color bar printed on the substrate. The system
may be run in a "Color Bar Mode" and scan simple rectangular color
patches corresponding to each ink key in the print units, or can
run in "Gray Spot Mode" and maintain overall target ink density
values on the substrate as well as gray balance if the job has
critical half tone images, or if the color bar is obtrusive on the
job.
Inventors: |
Friedman; Michael (Windsor,
NJ), Patel; Manojkumar (Princeton Junction, NJ), Patel;
Piyushkumar (Hamilton, NJ) |
Assignee: |
Innolutions, Inc. (Windsor,
NJ)
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Family
ID: |
43901331 |
Appl.
No.: |
12/660,634 |
Filed: |
March 2, 2010 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20110216120 A1 |
Sep 8, 2011 |
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Current U.S.
Class: |
347/19; 347/14;
347/5 |
Current CPC
Class: |
B41F
33/0045 (20130101); B41P 2233/51 (20130101) |
Current International
Class: |
B41J
29/393 (20060101) |
Field of
Search: |
;347/5,6,9,14,15,19,20 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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10-175290 |
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Jun 1998 |
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JP |
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11-165398 |
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Jun 1999 |
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JP |
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WO 95/11806 |
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May 1995 |
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WO |
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Primary Examiner: Jackson; Juanita D
Attorney, Agent or Firm: Roberts & Roberts, LLP
Claims
What is claimed is:
1. A process for measuring and controlling a color value of one or
more colored image portions which are printed on a planar
substrate, the process comprising: (a) providing one or more
colored image portions which are printed on a planar substrate,
each colored image portion comprising one or more colors produced
by one or more colored inks; (b) providing one or more pairs of
reference markers printed on the planar substrate in one or more
ink zones and positioned adjacent to said one or more colored image
portions, wherein each pair of reference markers comprises a
primary reference marker and a secondary reference marker; wherein
the primary reference marker comprises black ink and the secondary
reference marker comprises one or more of cyan, magenta and yellow
ink components; wherein each of said primary reference marker and
said secondary reference marker has an ink density value, wherein
said black, cyan, magenta and yellow inks each have an individual
ink density value when present; (c) providing at least one imaging
assembly, wherein the imaging assembly is capable of capturing
digital representations of each of said reference markers; (d)
controlling the positioning and linear movement of said imaging
assembly across the planar substrate; (e) selecting and acquiring a
digital image with the imaging assembly of the primary reference
marker and the secondary reference marker within one or more pairs
of reference markers in at least one ink zone; (f) analyzing the
digital image of the primary reference marker and the secondary
reference marker of each imaged reference marker pair to determine
the ink density value for each reference marker within each imaged
reference marker pair and the individual ink density values for
each ink component of each reference marker; (g) comparing the ink
density value of the primary reference marker and the ink density
value of the secondary reference marker of each imaged reference
marker pair and determining any difference between the ink density
value of said primary reference marker and the ink density value of
said secondary reference marker of said imaged reference marker
pair, and optionally storing said difference in a memory; (h)
optionally comparing the ink density value of the primary reference
marker and/or the ink density value of the secondary reference
marker of each imaged reference marker pair with a target ink
density value for at least a portion of the one or more colored
image portions on the substrate in at least one ink zone, and
determining any difference between the ink density value of the
primary reference marker and/or the ink density value of the
secondary reference marker of each imaged reference marker pair and
the target ink density value for the at least a portion of the one
or more colored image portions on the substrate in at least one ink
zone, and optionally storing said difference in a memory; (i)
optionally adjusting the ink quantity of black and/or colored ink
being printed onto the substrate such that the ink density value of
the primary reference marker in a reference marker pair is
equivalent to the ink density value of the secondary reference
marker in said reference marker pair, and/or such that the ink
density value of the primary reference marker and/or the ink
density value of the secondary reference marker in a reference
marker pair is equivalent to the ink density value of a manually
specified ink density value, and/or such that the ink density value
of the primary reference marker and/or the ink density value of the
secondary reference marker in a reference marker pair is equivalent
to the target ink density value for at least a portion of the one
or more colored image portions on the substrate in at least one ink
zone; and (j) optionally repeating steps (d)-(i) for at least one
of any additional ink zones.
2. The process of claim 1 wherein the secondary reference marker
comprises cyan, magenta and yellow ink components and wherein the
ink density value of the secondary reference marker equals the
combined individual ink density values of the cyan, magenta and
yellow ink components.
3. The process of claim 1 wherein the option of adjusting the ink
quantity on the substrate in step (i) is performed.
4. The process of claim 3 further comprising conducting steps (d)
through (i) to determine and compare the individual ink density
values for each of said cyan, magenta and yellow inks of said
secondary reference marker and adjusting the ink quantity of
colored ink being printed onto the substrate such that all three of
said individual ink density values are equivalent to each other
within said secondary reference marker, and optionally further
comparing the individual ink density values for each of said cyan,
magenta and yellow inks of said secondary reference marker with the
target ink density values of cyan, magenta and yellow inks in at
least a portion of the one or more colored image portions on the
substrate in at least one ink zone, and adjusting the ink quantity
of colored ink being printed onto the substrate such that all three
of said individual ink density values in said at least a portion of
the one or more colored image portions on the substrate in at least
one ink zone are equivalent to each corresponding individual ink
density value within said secondary reference marker.
5. The process of claim 3 comprising adjusting the ink quantity on
the substrate to change the ink density of the primary reference
marker, and thereafter changing the individual ink density values
of the cyan, magenta and yellow inks in said secondary reference
marker to approximately match the ink density value of the primary
reference marker.
6. The process of claim 3 wherein the planar substrate is moving
and one or more colored image portions are continuously printed on
the planar substrate, and wherein said ink quantity adjustment is
stopped if color fringes are detected around the edges of the
reference markers.
7. The process of claim 1 wherein the one or more colored image
portions are printed on the planar substrate in a plurality of ink
zones that extend across a width of the substrate, wherein one pair
of reference markers is printed in each ink zone.
8. The process of claim 1 wherein said imaging assembly comprises a
digital camera and at least one illumination source.
9. The process of claim 8 wherein the illumination source either
continuously or intermittently illuminates the one or more colored
image portions.
10. The process of claim 8 wherein the illumination source
comprises a strobe comprising one or more white light emitting
diodes.
11. The process of claim 8 wherein said image acquiring is
conducted by: (I) illuminating the substrate at the one or more
pairs of reference markers with the at least one illumination
source; and (II) capturing a digital image of the one or more pairs
of reference markers with the digital camera.
12. The process of claim 11 wherein the planar substrate is moving
and one or more colored image portions are continuously printed on
the planar substrate, and the illumination source and digital
camera move together across the substrate perpendicular to the
direction of travel of the substrate.
13. The process of claim 8 wherein the planar substrate is
stationary and the illumination source and digital camera move
together in two orthogonal directions relative to a surface of the
planar substrate.
14. The process of claim 1 wherein the one or more colored image
portions are printed on the planar substrate in a plurality of ink
zones that extend across a width of the substrate and wherein said
adjusting step (i) is performed by adjusting an ink control
mechanism to change the amount of ink printed onto the substrate in
one or more of said ink zones, thereby modifying the one or more
colored image portions printed on the planar substrate.
15. The process of claim 1 further comprising presenting a visual
representation of the one or more colored image portions, the one
or more pairs of reference markers, the primary reference marker,
the secondary reference marker, the ink density values of said
markers, a comparison of the ink density values, or combinations
thereof, on a display screen.
16. The process of claim 1 wherein the primary reference marker is
a halftone printed with black ink only.
17. The process of claim 1 wherein the ink density value of the
primary reference marker is equivalent to the ink density value of
the secondary reference marker, and said primary reference marker
is a halftone printed with black ink only.
18. The process of claim 1 wherein the primary reference marker and
the secondary reference marker are differentiated from other print
on the substrate by their geometry and/or their spatial
orientation.
19. The process of claim 1 wherein a position marker is printed on
the substrate relative to said primary reference marker and said
secondary reference marker, the process further comprising
verifying the lateral position of the primary reference marker
and/or the secondary reference marker on the substrate relative to
a location of the position marker.
20. A process for controlling an amount of ink fed from a plurality
of inking units in a multicolored printing press onto a planar
substrate fed through the press, which substrate is in a web or
sheet form, said substrate having one or more colored image
portions printed thereon from the inking units, which image
portions are printed across a width of the substrate in one or more
ink zones, each colored image portion comprising one or more
colors, wherein each color has an individual color value, the
system being capable of functioning in the presence of or absence
of a color bar, the process comprising: (a) providing one or more
colored image portions which are printed on a planar substrate,
each colored image portion comprising one or more colors produced
by one or more colored inks; (b) determining whether a color bar is
printed on the planar substrate, which color bar comprises a
plurality of color patches, wherein at least one color patch is
printed in each ink zone, wherein each color patch comprises one or
more color layers; and determining whether one or more pairs of
reference markers are printed on the planar substrate adjacent to
said one or more colored image portions and in one or more ink
zones, wherein each pair of reference markers comprises a primary
reference marker and a secondary reference marker; wherein the
primary reference marker comprises black ink and the secondary
reference marker comprises one or more of cyan, magenta and yellow
ink components; wherein each of said primary reference marker and
said secondary reference marker has an ink density value, wherein
said black, cyan, magenta and yellow inks each have an individual
ink density value when present, and wherein the ink density value
of the secondary reference marker optionally equals the combined
individual ink density values of the cyan, magenta and yellow inks;
(c) if one or more pairs of reference markers are present,
conducting step (I), and if a color bar is present, but no
reference markers are present, conducting step (II): (I) (i)
providing at least one imaging assembly, wherein the imaging
assembly is capable of capturing digital representations of each of
said reference markers; (ii) controlling the positioning and linear
movement of said imaging assembly across the planar substrate;
(iii) selecting and acquiring a digital image with the imaging
assembly of the primary reference marker and the secondary
reference marker within one or more pairs of reference markers in
at least one ink zone; (iv) analyzing the digital image of the
primary reference marker and the secondary reference marker of each
imaged reference marker pair to determine the ink density value for
each reference marker within each imaged reference marker pair and
the individual ink density values for each ink component of each
reference marker; (v) comparing the ink density value of the
primary reference marker and the ink density value of the secondary
reference marker of each imaged reference marker pair and
determining any difference between the ink density value of said
primary reference marker and the ink density value of said
secondary reference marker of said imaged reference marker pair,
and optionally storing said difference in a memory; (vi) optionally
comparing the ink density value of the primary reference marker
and/or the ink density value of the secondary reference marker of
each imaged reference marker pair with a target ink density value
for at least a portion of the one or more colored image portions on
the substrate in at least one ink zone, and determining any
difference between the ink density value of the primary reference
marker and/or the ink density value of the secondary reference
marker of each imaged reference marker pair and the target ink
density value for the at least a portion of the one or more colored
image portions on the substrate in at least one ink zone, and
optionally storing said difference in a memory; (vii) optionally
adjusting the ink quantity of black and/or colored ink being
printed onto the substrate such that the ink density value of the
primary reference marker in a reference marker pair is equivalent
to the ink density value of the secondary reference marker in said
reference marker pair, and/or such that the ink density value of
the primary reference marker and/or the ink density value of the
secondary reference marker in a reference marker pair is equivalent
to the ink density value of a manually specified ink density value,
and/or such that the ink density value of the primary reference
marker and/or the ink density value of the secondary reference
marker in a reference marker pair is equivalent to the target ink
density value for at least a portion of the one or more colored
image portions on the substrate in at least one ink zone; and
(viii) optionally repeating steps (ii)-(vii) for at least one of
any additional ink zones; (II) (i) providing at least one imaging
assembly, wherein the imaging assembly is capable of capturing
digital representations of each of said reference markers; (ii)
controlling the positioning and linear movement of said imaging
assembly across the planar substrate; (iii) selecting and acquiring
a digital image with the imaging assembly of one or more color
patches in a first ink zone; (iv) analyzing the acquired digital
image of the one or more color patches to determine an actual ink
density value for each color patch; (v) comparing the actual ink
density values of each color patch to a target ink density value
for each color patch and determining any difference between the
actual ink density value and the target ink density value for each
color patch, and optionally storing said difference in a memory;
and (vi) optionally adjusting the ink quantity being printed on the
substrate such that the actual ink density value of the one or more
color patches in the first ink zone is equivalent to the target ink
density value for each corresponding color patch; and (vii)
optionally repeating steps (ii)-(vi) for at least one additional
color patch in at least one of any additional ink zones.
Description
CD-ROM APPENDIX
The computer program listing appendix referenced, included and
incorporated in the present application is included in a single
CD-ROM appendix labeled "UNIVERSAL CLOSED LOOP COLOR CONTROL",
which is submitted in duplicate. The CD-ROM appendix includes 115
files. The computer program is incorporated herein by
reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a system for the accurate
measurement and control of image color values on a printing press
with or without the presence of a color bar. More particularly, the
invention provides a universal closed loop color control system and
processes for controlling the color quality of color images printed
on a substrate online or offline, with or without a color bar
printed on the substrate.
2. Description of the Related Art
Color perception of a printed image by the human eye is determined
by the light reflected from an object, such as a printed substrate.
Changing the amount of ink or other medium applied to a substrate
changes the amount of color on the printed substrate, and hence the
quality of the perceived image.
Each of the individual single images is produced with a specific
color ink, referred to in the art as "primary colors" or "process
colors". A multi-colored printed image is produced by combining a
plurality of superimposed single color printed images onto a
substrate. To create a multi-colored image, inks are applied at a
predetermined pattern and thickness, or ink density. The ink
patterns are generally not solid, but are composed of arrays of
dots which appear as solid colors when viewed by the human eye at a
distance. The images produced by such arrays of colored dots are
called halftones. The fractional coverage of the dots of a halftone
ink pattern combined with the solid ink density is referred to as
the optical density of the ink pattern. For example, when ink dots
are spaced so that half the area of an ink pattern is covered by
ink and half is not, the coverage of the ink pattern is considered
to be 50%.
The color quality of a multi-colored printed image is determined by
the degree to which the colors of the image match the desired
colors for the image, i.e. the colors of a reference image. Hence,
the obtained quality of a multi-color image is determined by the
density of each of the individual colored images of which the
multi-colored image is composed. An inaccurate ink density setting
for any of the colors may result in a multi-colored image of
inferior color quality. An offset printing press includes an inking
assembly for each color of ink used in the printing process. Each
inking assembly includes an ink reservoir as well as a segmented
blade disposed along the outer surface of an ink fountain roller.
The amount of ink supplied to the roller train of the press and
ultimately to a substrate, such as paper, is adjusted by changing
the spacing between the edge of the blade segments and the outer
surface of the ink fountain roller to change (either increase or
decrease) the amount of ink printed onto the substrate in one or
more ink zones (ink key zones). The position of each blade segment
relative to the ink fountain roller is independently adjustable by
movement of an ink control mechanism/device such as an adjusting
screw, or ink key (ink control key), to thereby control the amount
of ink fed to a corresponding longitudinal strip or ink zone of the
substrate, wherein an "ink zone" (or "ink key zone") refers to an
area of the substrate extending across a width of the substrate.
The ink control mechanism includes any device that controls the
amount of ink fed to a corresponding longitudinal strip or zone of
the substrate. The ink control keys each control the amount of ink
supplied to a respective ink zone on the substrate.
In the printing industry, color bars have been used for a long time
to measure ink density. A color bar comprises a series of color
patches of different colors in each ink zone, wherein each color
patch comprises one or more color layers. To achieve a desired
(i.e. target) ink density for printed information on a substrate,
the printing press operator measures the ink density of the color
patch or patches in one or more ink zones. The ink density of a
color is determined by the settings of the ink supply for the ink
of that color. A printing press operator adjusts the amount of ink
applied to the substrate to get a desired color having a desired
ink density. Opening an ink key increases the amount of ink along
its zone and vice versa. If the ink density of the patch is too
low, the operator opens the ink key to increase amount of ink
flowing to the substrate in the corresponding ink zone. If the ink
density of the patch is too high, the operator closes the ink key
to decrease the amount of ink flowing to the substrate. Generally,
it is assumed that the change in color density of the patches also
represents a similar change in the color density of the printed
image. However, this assumption is not always correct. To adjust
for this discrepancy, the press operator should take the color bar
patch density only as a guide, while final color adjustments are
made by visually inspecting the printed information, and also by
measuring the color ink density, or color values, of critical areas
in the print. Where used herein, the term "color" is used in
reference to black ink, as well as inks of primary process colors
cyan, magenta and yellow.
At the start of a printing run, the ink key settings for the
various color inks must be set to achieve the appropriate ink
density levels for the individual color images in order to produce
multicolor images with the desired colors. Additionally,
adjustments to the ink key settings may be required to compensate
for deviations in the printing process of colors during a printing
run. Such deviations may be caused by alignment changes between
various rollers in the printing system, the paper stock, web
tension, room temperature and humidity, among other factors.
Adjustments may also be required to compensate for printing process
deviations that occur from one printing run to another. In the
past, such ink density adjustments have been performed by human
operators based merely on conclusions drawn from the visual
inspection of printed images. However, such manual control methods
tended to be slow, relatively inaccurate, and labor intensive. The
visual inspection techniques used in connection with manual ink key
presetting and color control are inaccurate, expensive, and
time-consuming. Further, since the required image colors are often
halftones of ink combined with other ink colors, such techniques
also require a high level of operator expertise.
Methods other than visual inspection of the printed image are also
known for monitoring color quality once the press is running.
Methods have been developed to control ink supplies based on
objective measurements of the printed images. To conduct the task
of color density measurement, offline density measurement
instruments are available. Quality control of color printing
processes can be achieved by measuring the optical density of a
test target image. Optical density of various points of the test
target image can be measured by using a densitometer or scanning
densitometer either offline or online of the web printing process.
Typically, optical density measurements are performed by
illuminating the test target image with a light source and
measuring the intensity of the light reflected from the image. For
example, a press operator takes a sample of printed substrate with
the color bars and puts it in the instrument. A typical instrument
has a density scanning head traveling across the width of the color
bars. After scanning, the instrument displays density measurements
on a computer screen. Upon examining the density values on display
and also examining the printed sample, the operator makes necessary
changes to the ink keys. This procedure is repeated until
satisfactory print quality is achieved.
To automate this task, online density measurement instruments are
known. While the press is running, it is common for a press
operator to continually monitor the printed output and to make
appropriate ink key adjustments in order to achieve appropriate
quality control of the color of the printed image. For example, if
the color in a zone is too weak, the operator adjusts the
corresponding ink key to allow more ink flow to that zone. If the
color is too strong, the corresponding ink key is adjusted to
decrease the ink flow. During operation of the printing press,
further color adjustments may be necessary to compensate for
changing press conditions, or to account for the personal
preferences of the customer.
Online instruments comprise a scanning assembly mounted on the
printing press. The test target image that is measured is often in
the form of a color bar comprised of individual color patches. The
color bar typically extends the width of the substrate (see FIG.
7). Typically, color bars are scanned on the printing press at the
patches, which include solid patches and halftone patches for each
of the primary ink colors, as well as solid overprints. The color
bar is often printed in the trim area of the substrate and may be
utilized for registration as well as color monitoring purposes.
Each solid patch has a target density that the color control system
attempts to maintain. The inking level is increased or decreased to
reach this target density.
Instruments that can measure density on the press and also
automatically activate ink keys on the press to bring color density
to a desired value are commonly known as Closed Loop Color
Controls. A Closed Loop Color Control is primarily used to perform
three tasks. The first task is to analyze the image from pre-press
information to find the coverage of different colors in different
ink zones and preset the ink fountain key openings to get the
printed substrate close to the required colors. Ink key opening
presets are just an approximation and may not be a perfect setting.
The second task is to analyze the color information scanned from
the substrate being printed on the press, compare it with the
desired color values and make corrections to the ink key openings
to achieve the desired color values. The third task is to
continuously analyze the printed substrate and maintain color
values throughout the job run length.
Different density measuring instruments vary in the way they scan
color bars and calculate color patch density. Different scanning
methods can be categorized into two groups. A first group uses a
spectrophotometer mounted in the imaging assembly. A video camera
and strobe are used to freeze the image of moving substrate and
accurately locate color bars. The spectrophotometer is then aligned
to a color patch and it is used to take a reading of the color
patch. For positioning color patches in the longitudinal Y
direction of the substrate, a cue mark and a photo sensor are used.
For distinguishing color patches from print, a special shape of
color patch is required for this instrument. A second group uses
video cameras mounted in an imaging assembly. Typically, a color
camera with a strobe is used to freeze the motion of the moving
substrate and acquire an image. Most manufacturers use a three
sensor camera, in which prisms are used to split red, green and
blue channels. Analog signals from these three channels are fed to
frame acquiring electronics to digitize and analyze image.
Most manufacturers use xenon strobes for illuminating the moving
substrate for a short period of time. Xenon strobes work on the
principle of high voltage discharge through a glass tube filled
with xenon gas. It is well known that the light intensity from
flash to flash with such a device is not consistent. This becomes a
problem in color measurement since variation in flash intensity
provides false readings. To overcome this problem, a system
described in U.S. Pat. No. 6,058,201 uses a light output
measurement device in front of the strobe and provides correction
in color density calculations. Another problem with xenon strobes
is that they work with higher voltage and drive electronics
generate electrical noise and heat. These features make it more
difficult to package a camera and xenon strobe in a single sealed
imaging assembly. Another prior system described in U.S. Pat. No.
5,992,318 mounts the strobe away from the camera and transmits
light through a light pipe.
To overcome these problems, it is desirable to use white light
emitting diode (LED) light strobes with a single sensor color
camera to measure color values on the color bar to accomplish
closed loop color operation on the press. White LEDs provide a
light source with very consistent light from flash to flash. Also,
the LEDs operate at a very low voltage and current. This reduces
heat generation in the imaging assembly and it also eliminates
electrical noise typically associated with xenon light strobes.
All of the above mentioned methods use a color bar with a
combination of solid and tint patches to measure the color across
the width of the substrate. Unfortunately, measuring the color of a
printed substrate using a color bar has several disadvantages.
First, it is an indirect method of measuring color in the print,
whereby it is assumed that the change in color density of a patch
in the color bar represents the change in the color value of the
printed substrate in the longitudinal zone aligned with the
measured patch. However, this assumption is not always correct.
Second, the color bar requires additional space on the substrate.
Depending on job configuration, this space may not be available.
Further, this additional substrate space is not part of the
finished product, so it increases the cost of production. In
addition, there are associated trimming costs for printed products
for which a color bar is objectionable, thereby increasing the cost
of the operation, as well as the costs associated with removing and
disposing of trimmed color bar waste.
Alternatively, measuring the color of a printed substrate with a
color bar does have its advantages. First, a color bar provides
dedicated patches for each color that can be measured by the
control as well as by the press operators using hand held color
measuring instruments. Further, different types of patches (such as
25% tint, 50% tint, 75% tint, trap overprint) can be printed to
check overall performance including pre-press settings, ink and
water balance.
For different press configurations and job requirements, it may or
may not be possible to have color bars. While a color bar may have
some advantages, the job and press configuration may not allow
having a color bar. In such a case, the operator has to adjust the
press by visually inspecting the image or by measuring the color
value within the print using a hand held densitometer, and the
operator has to choose the places where he would like to measure
the color value, and the densitometer readings may not be correct
if colors are mixed in the area being inspected. Due to the
obstacles associated with color bars, it is desirable to provide an
option to eliminate the color bar and automate the image inspection
to significantly improve the overall efficiency of the printing
process.
Several attempts have been made to measure color values in an image
directly from a printed substrate. A number of past efforts have
been explored through which color information on a print can be
acquired and analyzed. For example, U.S. Pat. No. 5,967,050 teaches
a method which takes images of a printed substrate and aligns the
obtained image with a reference image from available pre-press
information and calculates color error on pixel-by-pixel basis. The
operation requires a lot of computation power making it very
expensive and slow. These requirements make it practically
impossible to implement Closed Loop Color Control without a color
bar.
Another method of getting color information in each ink zone may
involve taking multiple images in an ink zone and aligning and
analyzing the images with the corresponding locations on the image
information from the pre-press information on a pixel-by-pixel
basis. This would also require a lot of computation power since
images in the same ink zone have to be captured, aligned to the
pre-press image, processed and analyzed.
Yet another method of getting the color information in each ink
zone is by positioning a camera in an ink zone, illuminating the
region under camera with a constant illumination light source (i.e.
non-strobing) and keeping the camera shutter open for a certain
time. In order to get a correct color reading, the shutter opening
and closing should be synchronized with the substrate movement such
that the number of press repeats passing under the camera are exact
multiples, otherwise color information for the partial press repeat
scanned is also added to the reading. Since color values read from
the camera are dependent on the amount of light received by the
sensor in a specific time, this method becomes speed sensitive. Any
variation due to change in speed has to be compensated
mathematically or by changing the light illumination intensity.
Both solutions suffer from inherent inaccuracies and errors making
it practically very difficult to implement this solution. This
system is further disadvantageous because the light reflected from
non-printed areas also gets integrated into the frame. If there is
heavy coverage of various colors, the resulting integrated frame
shows a very dark and gray looking frame. If there is a very small
area being printed on the ink zone, the image of printed area gets
diluted by the image of the non-printed area of the substrate to a
point where the final frame may not be able to provide enough
resolution information about the printed color.
A further method of obtaining color information in each ink zone is
by keeping the camera shutter open for a time greater than the time
for one press repeat to pass under the camera and using a strobe
light to illuminate several sections of the ink zone and using the
charge-coupled device (CCD) in the camera to accumulate the
reflected color value for the whole repeat length. This method
relies on the fact that the frame produced by such integration
(multiple exposures) is a representative of total color in the ink
zone area. The disadvantage of this system is that the light
reflected from non-printed areas also gets integrated in the frame.
If there is heavy coverage of various colors, the resulting
integrated frame shows a very dark and gray looking frame. If there
is a very small area being printed on the ink zone, the image of
printed area gets diluted by the image of the non-printed area of
the substrate to a point where the integrated frame may not be able
to provide enough resolution information about the printed
color.
The present invention provides an improved approach to measure
color values on a printed substrate, where gray balance is
monitored as well as overall color saturation in a printed image.
The system of the present invention is capable of operation in
either "Color Bar with Solid Ink Density" or "Gray Spot with Gray
Balance" modes, where an operator has the choice to implement
Closed Loop Color Control with or without a color bar printed on
the substrate as per the methods of commonly owned U.S. Pat. Nos.
7,187,472 and 7,477,420, combined with the additional Gray Spot
with Gray Balance feature of the present invention. More
particularly, a Universal Closed Loop Color Control system is
provided that allows real-time, four process color control and
monitoring on a printing press using obscure gray dots printed in
the page margins rather than color bars. The gray dots are
unobtrusive, do not attract the eye and need not be trimmed, saving
cost in labor and disposal. The system is universal by allowing the
operator to choose and easily switch between the inventive gray
spot (i.e. gray reference marker) analysis and conventional color
bar analysis. The inventive system provides an alternative in the
art for an efficient and inexpensive method for closed loop color
control by allowing for measurement and determination of color
density variations, as well as for controlling the plurality of ink
control mechanisms, or ink keys, on a printing press for on-the-run
color correction whether a color bar is present or not.
The process of the present invention is compatible with the
operation of a printing press, such as sheet fed and web presses,
and offset printing, Gravure printing, Flexo printing and generally
any other printing processes. The system can communicate with the
latest press controls as well as older presses for scanning,
measuring and correcting color on the run.
SUMMARY OF THE INVENTION
The invention provides a process for measuring and controlling a
color value of one or more colored image portions which are printed
on a planar substrate, the process comprising: (a) providing one or
more colored image portions which are printed on a planar
substrate, each colored image portion comprising one or more colors
produced by one or more colored inks; (b) providing one or more
pairs of reference markers printed on the planar substrate in one
or more ink zones and positioned adjacent to said one or more
colored image portions, wherein each pair of reference markers
comprises a primary reference marker and a secondary reference
marker; wherein the primary reference marker comprises black ink
and the secondary reference marker comprises one or more of cyan,
magenta and yellow ink components; wherein each of said primary
reference marker and said secondary reference marker has an ink
density value, wherein said black, cyan, magenta and yellow inks
each have an individual ink density value when present; (c)
providing at least one imaging assembly, wherein the imaging
assembly is capable of capturing digital representations of each of
said reference markers; (d) controlling the positioning and linear
movement of said imaging assembly across the planar substrate; (e)
selecting and acquiring a digital image with the imaging assembly
of the primary reference marker and the secondary reference marker
within one or more pairs of reference markers in at least one ink
zone; (f) analyzing the digital image of the primary reference
marker and the secondary reference marker of each imaged reference
marker pair to determine the ink density value for each reference
marker within each imaged reference marker pair and the individual
ink density values for each ink component of each reference marker;
(g) comparing the ink density value of the primary reference marker
and the ink density value of the secondary reference marker of each
imaged reference marker pair and determining any difference between
the ink density value of said primary reference marker and the ink
density value of said secondary reference marker of said imaged
reference marker pair, and optionally storing said difference in a
memory; (h) optionally comparing the ink density value of the
primary reference marker and/or the ink density value of the
secondary reference marker of each imaged reference marker pair
with a target ink density value for at least a portion of the one
or more colored image portions on the substrate in at least one ink
zone, and determining any difference between the ink density value
of the primary reference marker and/or the ink density value of the
secondary reference marker of each imaged reference marker pair and
the target ink density value for the at least a portion of the one
or more colored image portions on the substrate in at least one ink
zone, and optionally storing said difference in a memory; (i)
optionally adjusting the ink quantity of black and/or colored ink
being printed onto the substrate such that the ink density value of
the primary reference marker in a reference marker pair is
equivalent to the ink density value of the secondary reference
marker in said reference marker pair, and/or such that the ink
density value of the primary reference marker and/or the ink
density value of the secondary reference marker in a reference
marker pair is equivalent to the ink density value of a manually
specified ink density value, and/or such that the ink density value
of the primary reference marker and/or the ink density value of the
secondary reference marker in a reference marker pair is equivalent
to the target ink density value for at least a portion of the one
or more colored image portions on the substrate in at least one ink
zone; and (j) optionally repeating steps (d)-(i) for at least one
of any additional ink zones.
The invention also provides a process for controlling an amount of
ink fed from a plurality of inking units in a multicolored printing
press onto a planar substrate fed through the press, which
substrate is in a web or sheet form, said substrate having one or
more colored image portions printed thereon from the inking units,
which image portions are printed across a width of the substrate in
one or more ink zones, each colored image portion comprising one or
more colors, wherein each color has an individual color value, the
system being capable of functioning in the presence of or absence
of a color bar, the process comprising: (a) providing one or more
colored image portions which are printed on a planar substrate,
each colored image portion comprising one or more colors produced
by one or more colored inks; (b) determining whether a color bar is
printed on the planar substrate, which color bar comprises a
plurality of color patches, wherein at least one color patch is
printed in each ink zone, wherein each color patch comprises one or
more color layers; and determining whether one or more pairs of
reference markers are printed on the planar substrate adjacent to
said one or more colored image portions and in one or more ink
zones, wherein each pair of reference markers comprises a primary
reference marker and a secondary reference marker; wherein the
primary reference marker comprises black ink and the secondary
reference marker comprises one or more of cyan, magenta and yellow
ink components; wherein each of said primary reference marker and
said secondary reference marker has an ink density value, wherein
said black, cyan, magenta and yellow inks each have an individual
ink density value when present, and wherein the ink density value
of the secondary reference marker optionally equals the combined
individual ink density values of the cyan, magenta and yellow inks;
(c) if one or more pairs of reference markers are present,
conducting step (I), and if a color bar is present, but no
reference markers are present, conducting step (II): (I) (i)
providing at least one imaging assembly, wherein the imaging
assembly is capable of capturing digital representations of each of
said reference markers; (ii) controlling the positioning and linear
movement of said imaging assembly across the planar substrate;
(iii) selecting and acquiring a digital image with the imaging
assembly of the primary reference marker and the secondary
reference marker within one or more pairs of reference markers in
at least one ink zone; (iv) analyzing the digital image of the
primary reference marker and the secondary reference marker of each
imaged reference marker pair to determine the ink density value for
each reference marker within each imaged reference marker pair and
the individual ink density values for to each ink component of each
reference marker; (v) comparing the ink density value of the
primary reference marker and the ink density value of the secondary
reference marker of each imaged reference marker pair and
determining any difference between the ink density value of said
primary reference marker and the ink density value of said
secondary reference marker of said imaged reference marker pair,
and optionally storing said difference in a memory; (vi) optionally
comparing the ink density value of the primary reference marker
and/or the ink density value of the secondary reference marker of
each imaged reference marker pair with a target ink density value
for at least a portion of the one or more colored image portions on
the substrate in at least one ink zone, and determining any
difference between the ink density value of the primary reference
marker and/or the ink density value of the secondary reference
marker of each imaged reference marker pair and the target ink
density value for the at least a portion of the one or more colored
image portions on the substrate in at least one ink zone, and
optionally storing said difference in a memory; (vii) optionally
adjusting the ink quantity of black and/or colored ink being
printed onto the substrate such that the ink density value of the
primary reference marker in a reference marker pair is equivalent
to the ink density value of the secondary reference marker in said
reference marker pair, and/or such that the ink density value of
the primary reference marker and/or the ink density value of the
secondary reference marker in a reference marker pair is equivalent
to the ink density value of a manually specified ink density value,
and/or such that the ink density value of the primary reference
marker and/or the ink density value of the secondary reference
marker in a reference marker pair is equivalent to the target ink
density value for at least a portion of the one or more colored
image portions on the substrate in at least one ink zone; and
(viii) optionally repeating steps (ii)-(vii) for at least one of
any additional ink zones; (II) (i) providing at least one imaging
assembly, wherein the imaging assembly is capable of capturing
digital representations of each of said reference markers; (ii)
controlling the positioning and linear movement of said imaging
assembly across the planar substrate; (iii) selecting and acquiring
a digital image with the imaging assembly of one or more color
patches in a first ink zone; (iv) analyzing the acquired digital
image of the one or more color patches to determine an actual ink
density value for each color patch; (v) comparing the actual ink
density values of each color patch to a target ink density value
for each color patch and determining any difference between the
actual ink density value and the target ink density value for each
color patch, and optionally storing said difference in a memory;
and (vi) optionally adjusting the ink quantity being printed on the
substrate such that the actual ink density value of the one or more
color patches in the first ink zone is equivalent to the target ink
density value for each corresponding color patch; and (vii)
optionally repeating steps (ii)-(vi) for at least one additional
color patch in at least one of any additional ink zones.
The method of the invention is a universal closed loop color
control system that may be run in a color bar mode and scan simple
rectangular color patches corresponding to each ink zone in the
print units, or can run in gray spot mode and maintain gray balance
if the job has critical half tone images, or if the color bar is
obtrusive on the job. This choice of mode of operation is made by
the operator. This new system works in concert with all modes of
operation described in commonly owned U.S. Pat. No. 7,187,472
(color bar process, i.e. "CCC") and U.S. Pat. No. 7,477,420
(barless process, i.e. without a color bar, i.e. "BCC"), and the
disclosures and computer programs of these two patents are
incorporated herein by reference to the extent not inconsistent
herewith, giving the operator the choice of color control at the
time of running the job. In the present inventive process, each
time a colored target (color patch or reference marker (grey or
multi-color) passes under the imaging assembly, a custom LED strobe
as described in commonly owned U.S. Pat. Nos. 7,187,472 and
7,477,420 illuminates the patch area/reference marker area for
microseconds and an image is acquired with a color camera. The
central processing unit (CPU)/processor recognizes the colored
targets and accurately calculates their color values. Based on
these values, the CPU sends commands to remote processors for
adjusting individual ink keys.
Equipped with a fountain presetting feature, the system of the
present invention can significantly reduce startup waste and
provide consistent quality throughout a run. The closed loop color
control process of the invention is especially designed for high
speeds web presses, and includes a "Scan Accelerator Mode" that
significantly reduces the total scan time across the substrate. The
system is also capable of choosing optimum ink stroke settings in
addition to presetting the ink keys, allowing the press operator to
override recommended ink stroke settings. The system is also
capable of adjusting ink stroke in automatic mode to keep ink keys
and ink stroke balanced.
In the preferred embodiments of the invention, the inventive system
preferably, but not necessarily, provides one or more of the
following features and benefits: For the color bar mode, the
patches may be as small as 0.06''.times.0.14'' (1.5 mm.times.3.5
mm) or any other standard size, with only 0.010'' white space
around color patches. In color bar mode, the system tracks solid
ink density, dot gain, print contrast, and grayness, and supports
PMS colors. In gray spot mode, the reference markers may be round
spots as small as 0.06'' diameter. The unique image pattern
recognition of the invention is very tolerant to misregistration,
and has excellent tolerance to blanket wash print disturbance. The
inventive system may be used with 10 print units, with 2 web (4
surface) configuration and up to 72'' wide web width. The system
includes auto tracking for immunity to web tension changes during
splice cycle or lateral weave +/-0.5'' (12 mm). The system also
utilizes existing motorized ink keys, minimizing installation cost
and down time, and a small format camera stand is incorporated for
easy incorporation into existing press configuration. The system
uses CIP3 file analysis for image preview and fountain presetting,
utilizes a paper library that supports both SWOP and custom paper
types, and utilizes an integrated spot densitometer with
programmable regions of interest. The system also allows operators
to verify print live on the web using Universal Closed Loop Color
Control (UCC) imaging, allows real time color image display during
scan cycle, and presents statistical results that display current
measurements compared with pre-programmed standards. Other features
include statistical quality reporting, an out of range statistical
quality alarm, and standard stroke and water control. A virtually
unlimited number of jobs can be stored, using job files to store
ink key position, ink stroke and water settings, plus target color
for each ink key on every ink fountain. The user interface is easy
to learn, has online context-sensitive help, flat panel touch
screen operation, and a practically maintenance free imaging
assembly with a 100,000+ hour average LED strobe life. The majority
of system components are commercially available from various
sources, with optional multiple operator consoles are available for
remote operations.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a flowchart showing a system overview of the inventive
color control system.
FIG. 2 is a flowchart showing an overview of a color bar
recognition process using the inventive color control system.
FIG. 3 is a block diagram of a print unit controller for the
inventive color control system.
FIG. 4 is a block diagram of an upper/lower fountain control buss
operation for a fountain key adapter for the inventive color
control system.
FIG. 5 is a block diagram of strobe and camera control
functions.
FIG. 6A and FIG. 6B are perspective and side views of equipment for
scanning a printed substrate by mounted strobes and cameras.
FIG. 7 is a schematic representation of color bars and color
patches, which are printed on a substrate.
FIG. 8A is side perspective view of an imaging assembly according
to the invention.
FIG. 8B and FIG. 8C show single and multiple light source strobes
respectively.
FIG. 9 illustrates an arrangement with a stationary substrate and a
moving imaging assembly.
FIG. 10 illustrates the typical nature and layout of print and ink
zones on the substrate.
FIG. 11 is a flowchart illustrating the image acquisition process
for getting color information for each ink zone according to the
invention.
FIG. 12A is a schematic representation of a pair of reference
markers in relation to each other.
FIG. 12B is a schematic representation of a position marker in
between primary and secondary reference markers.
FIG. 13 is a schematic representation of reference markers in
relation to a substrate, having one pair of reference markers
within each ink zone.
DETAILED DESCRIPTION OF THE INVENTION
The invention provides a system and processes for measuring and
controlling the color values of one or more colored images or
colored image portions during operation of a printing press, such
as sheet fed and web presses, and offset printing, Gravure
printing, Flexo printing and generally any other printing
processes. The images being printed comprise one or more colors and
are printed on a moving, planar substrate in one or more ink zones
that extend across a width of the substrate. Using the equipment of
either of commonly owned U.S. Pat. Nos. 7,187,472 or 7,477,420,
color quality of the printed images are monitored and controlled by
selecting and acquiring images of one or more pairs of reference
markers on a moving or stationary substrate, determining a
relationship between the reference markers within each pair, and
automatically making any necessary ink quantity adjustments to
equilibrate the ink density values of each reference marker within
each pair.
It should be understood that when the term "color" is used herein,
the term includes black as a color as well as cyan, magenta or
yellow. It should also be understood that when the term "ink" is
used herein, the term is intended to include toners, pigments, dyes
and other colored substances and compositions commonly used to
print text and images in the printing industry.
In a typical rotary printing process, printing cylinders having
printing plates attached thereto are utilized. Conventionally, a
positive or negative image is put onto a printing plate using
standard photomechanical, photochemical or engraving processes. Ink
is then applied to the plate's image area and transferred to the
substrate. A single printing plate is generally used for each color
used in forming the image. In a typical printing operation, printed
images are formed from a combination of overlapping color layers of
the process colors cyan, magenta, yellow, which are known in the
art of printing as "primary colors", and black. Accordingly, at
least four printing plates are typically used, one for each of
those colors. Non-process colors may also be added to the color
image by the use of additional plates.
As is well known in the art, when using a printing press, an image
is repeatedly printed on a substrate and the print repeat length is
equal to the circumference of the printing cylinder. In a typical
printing press, an ink fountain provides the ink for the printing
operation. The ink fountain may have several ink keys across the
width of the fountain. Each ink key can be individually opened or
closed via an ink control mechanism to allow more or less ink onto
the corresponding ink zone (conventionally longitudinal) on the
substrate. FIG. 10 offers an illustration of a substrate divided
into multiple ink zones. Ink from the ink fountain may travel down
an ink train through distributor rollers, and any change in the
setting of an ink key affects the whole longitudinal path aligned
with the ink zone. A typical printing press also has oscillator
rollers. In addition to rotational motion, these oscillator rollers
also have axial motion moving back and forth. The axial motion
spreads ink along the ink zone to the adjacent ink zones.
According to the process of the invention, during the running of
the press, the color values of reference markers are monitored
through scanning the substrate surface with the imaging assembly,
preferably continuously, to maintain the known difference between
the ink density of a primary reference marker and the ink density
of a secondary reference marker of one or more pairs of reference
markers. Most preferably the ink densities of the primary and
secondary reference markers are equal, and thus there is no
difference between their ink densities, and that equilibrium is
preferably maintained. The overall ink density of one or both of
said reference markers is also preferably compared, preferably
continuously, to a target ink density value for at least a portion
of the colored image/one or more colored image portion(s) on the
substrate in order to maintain an even ink density across the
substrate, wherein the target ink density value for each individual
color across the substrate, e.g. each individual color in each ink
zone, and the ink density of one or both of the primary and
secondary reference markers, are compared and preferably maintained
at equilibrium. These target ink density values for the colored
image/colored image portion(s) on the substrate may be obtained
from provided pre-press information or may be identified via the
methods described in commonly owned U.S. Pat. Nos. 7,187,472 and
7,477,420. During scanning of the printed substrate, images are
taken of the substrate at the reference markers and the images are
analyzed to determine updated ink density values for each color
present, preferably comparing the reference markers to each other
as well as to the target ink density values for the colored
image/colored image portion(s) on the substrate.
More specifically, in gray spot mode, the system computer/processor
(CPU) will determine the difference, if any, between the primary
and secondary reference markers, which will correspond to the
balance of the colors for each color as present in one or more ink
zones. If there is a difference, i.e. if the ink density of the two
reference markers is not equivalent, then an ink quantity
adjustment will automatically be made on the substrate in the
corresponding ink zone to bring the ink densities of the primary
reference marker and the secondary reference marker into
equilibrium. This will maintain the ink density values at the
desired level as provided by pre-press information, as manually
specified/set by the operator, or as otherwise generated. This
process may be repeated continuously during the entire printing
operation as may be desired, and these steps of analyzing color
balance and making any necessary adjustments to the color values
for each color in each ink zone are preferably continuously
performed on the press for the complete job run length.
Accordingly, the system of the invention monitors both gray balance
and overall ink density of the ink being printed on the substrate,
such that the colors being printed are both balanced and even
across the page.
The technique used to do this is the same as used in the CCC device
described in commonly owned U.S. Pat. No. 7,187,472. It should be
understood that a press operator may also override any color values
provided by pre-press information, as manually set by the operator,
or otherwise generated, modify the colors being printed on the
substrate, and then maintain the modified colors via the reference
markers. If the colors are so modified, the substrate is then
scanned with a scanner, e.g. the imaging assembly or other scanner,
to determine modified color values, which are then monitored in the
same manner. It should be further understood that ink densities
(color values) may be affected by the characteristics of the
substrate being printed on, e.g. matte or glossy paper, and this
must be further taken into consideration in determining the ink
densities. Typically, these substrate specific considerations will
be taken into consideration by system software simply by
registering the substrate type being used. In the preferred
embodiment of the invention, an optical scatter computation and
correction is also conducted for both gray spot and color bar
readings.
In a preferred embodiment of the invention, the imaging assembly
will also recognize and adjust for any physical movement of the
substrate during the printing operation. This may be done on a
regular basis to ascertain the alignment between the imaging
assembly position and printed area corresponding to the ink zones.
This is required because the path of the paper through the press is
known to vary due to both press related and outside influence. This
alignment step may also be performed after specific events on the
press that may disturb the position of the substrate
circumferentially or laterally. Some of the examples of such events
are substrate roll splicing and blanket washing.
As mentioned herein, a preferred apparatus for use in the present
invention is described in commonly owned U.S. Pat. No. 7,187,472.
Described more specifically, the system of the present invention,
Universal Closed Loop Color Control, preferably comprises one
imaging assembly per surface scanned, each preferred imaging
assembly (see FIG. 6A and FIG. 8A (810)), preferably comprising the
following: 1. A commercially available color camera, FIG. 8A, 806
(e.g. Sony DFW-VL500). The camera preferably uses an interface such
as IEEE1394, USB2, Ethernet, etc., for setup as well as
transferring the image into a computer. No special frame grabber or
other hardware is required to transfer the image from camera. The
camera preferably has built in motorized zoom, motorized iris and
motorized focus control that can be easily controlled using the
IEEE1394 interface from the computer. Each camera has a unique
serial number stored in its memory and is individually addressable.
The exposure and other image processing are manually controllable
to ensure precisely repeatable images from frame to frame. Finally,
the camera may be triggered at a precise time, with accuracy to
microseconds, to ensure capturing the desired color sample. 2. An
illumination source, FIG. 5, FIGS. 8A-8C, 812: To overcome problems
of xenon strobes, white LED light strobes are preferably used to
freeze the image of a moving substrate, i.e. a substrate in motion
on a printing press. Since white LEDs are available with different
color temperature specifications, a grade suitable for the optimum
setting of the camera is selected and white balance is achieved by
manually setting camera parameters. Very bright LEDs are available
and preferred. The light assembly can have one point light source,
FIG. 8, 820, or an array of multiple light sources, FIG. 8, 840, to
provide the required strobe light brightness. In general, any
illumination source may be used, but a white LED light strobe as
described herein is the most preferred illumination source.
Camera trigger pulse width and its timing relationship to the
strobe are very important. The strobe's electronics will condition
the input trigger signal for appropriate camera triggering. Power
for the imaging assembly is preferably provided from a commercially
available 24 VDC switching power supply. A trigger input signal is
generated by a counter board mounted in the computer, FIG. 1, 100,
driven from a quadrature encoder, FIG. 1, 126, coupled to one
printing cylinder on the press. This is used to synchronize the
camera to the printed image in order to obtain the desired
black/color samples.
Each imaging assembly further preferably comprises a linear drive
for moving the illumination source and digital camera together
across the substrate. This linear drive allows the imaging assembly
to be moved in a direction perpendicular to the direction of travel
of a moving substrate, and allows the imaging assembly to move in
two orthogonal directions relative to a surface of a stationary
substrate. In the preferred embodiment, each imaging assembly is
preferably mounted on a carrier bracket moving on a track and guide
system, FIG. 6A, 622. A linear drive in the form of a motor with an
embedded microcontroller, FIG. 6A, 620, is preferably installed on
the carrier bracket. A timing pulley is preferably installed on the
shaft of the motor. A stationary timing belt is preferably
installed with two ends anchored to the brackets near the opposite
ends of travel of the imaging assembly. A proximity sensor
preferably is provided at one or both ends of the track and allows
the system to sense the end of travel for the imaging assembly. The
motor preferably communicates with the computer through an RS-485
network, FIG. 1, 140. All devices on the RS-485 network are
preferably individually addressable. Each imaging assembly motor is
programmed with a different network address and performs
independently of the other motors and assemblies.
The UCC engine is a computer, FIG. 1, 100, that preferably
comprises the following items: 1. A Pentium.RTM. processor based
motherboard. It also incorporates serial ports, parallel ports, a
floppy disk controller, hard drive controller, USB ports and
expansion slots. 2. A power supply for supplying appropriate DC
power as required. 3. A hard disk drive for permanently storing the
operating system, application programs and data. 4. A CD-ROM drive
to accept portable and/or transient programs and data. 5. A floppy
disk drive to accept portable and/or transient programs and data.
6. A video controller board and display monitor to provide the user
interface. 7. An IEEE1394 (Firewire) interface card with multiple
ports to communicate with cameras. 8. An Ethernet networking
interface card to communicate with consoles and other devices on
the network. 9. A USB port to interface with other devices. 10. An
Input/Output board to interface with the printing press and other
devices. 11. A counter board to take quadrature and index signals
from the encoder and provide trigger signals to the appropriate
imaging assembly.
An external RS-232 to RS-485 converter is preferably provided for
communication with the imaging assembly positioning motors and
print unit controllers in the system. While RS-232 is the standard
for personal computers, the RS-485 standard provides additional
margins against communications errors and increased signaling
distance in the industrial environment. Single or multiple user
consoles, FIG. 1, 136, 138, with touch screens preferably
communicate with the engine using the Ethernet backbone, FIG. 1,
128.
The engine also communicates with one or more print unit
controllers (PUCs) (see FIG. 3) to set and read ink key positions,
water settings, ink stroke settings and other print unit functions.
In addition to this, the print unit controller reports any faults
and exceptions information to the engine. The engine can
communicate with PUCs manufactured by any provider with a suitable
protocol.
The engine can also communicate with a pre-press system, FIG. 1,
130, to get job settings, printed image data and ink key presetting
data. The standard format in the industry is called the CIP3 file
format, but other file formats can also be used to communicate job
specific details from the pre-press software to the engine.
A console preferably comprises a computer with an Ethernet network
adapter and a touch screen. All common operations for the system
are performed using the touch screen of the console, though some
maintenance operations may need to be performed directly on the
engine using its local keyboard, mouse and video screen. The
console application program can also run on the same hardware as
the engine. In such a case, an additional separate computer will
not be required for the console.
An encoder is installed on the printing press coupled to the
printing cylinder. The encoder has three channels--channel A,
channel B and channel Z. Channels A and B are in a quadrature
relationship with each other. Typical channel resolution is 2500
pulses per revolution of the encoder shaft yielding 10,000 pulses
per revolution of encoder shaft. Channel Z provides one index pulse
per revolution of the encoder shaft. All three channel signals are
connected to the counter board in the engine. The function of the
counter board is to reliably count each encoder pulse and provide
accurate print cylinder position information. The engine can set at
least one count value into the counter board per printed surface.
When the encoder count matches this value, the counter board
activates an output trigger pulse for the corresponding surface,
initiating image acquisition from the camera and illumination
source, e.g. strobe. Thus, the image location may correspond to
anywhere on the printed substrate and the engine will still be able
to synchronize the imaging assembly.
Printing press interface signals are read and set using the
Input/Output board. Typical signals read from the press are press
printing, blanket wash, and press inhibit. These are used to
determine when accurate imaging may commence. Outputs from the
system are provided to reset the imaging assemblies, and produce
quality alarms and scan error alerts. Based on press installation
requirements, the Input/Output board may be substituted with USB
based or other I/O devices performing the same function.
The invention further comprises a display screen for presenting a
visual representation of information, including the one or more
colored image portions, the one or more pairs of reference markers,
the ink density values of the primary and secondary reference
markers, the individual ink density values of the cyan, magenta,
yellow and/or black inks, ink density value comparison data,
digital images of the colored image portions or digital images of
the reference markers, or combinations thereof. This display screen
preferably comprises said console.
The UCC apparatus is able to function both in the presence of a
color bar and in the absence of a color bar, using gray spot
analysis when the color bar is absent. Illustrated in FIG. 12A is a
schematic representation of a pair of reference markers in relation
to each other. Pairs of gray reference markers are printed on each
image produced by the printing press in order to determine a
balance of the colors being printed from each print unit. The
associated artwork for the reference markers is provided by the
present UCC program. A reference marker pair/pattern may be printed
in one or more ink zones, and if multiple ink zones are present may
be printed in all or only some of the ink zones. Preferably, but
not necessarily, a reference marker pair/pattern repeats for each
ink key in the print fountain (ink zone on the substrate). When a
plurality of reference marker pairs are present, they are scanned
by the imaging assembly either sequentially or simultaneously, but
typically sequentially along the present ink zones. The resulting
ink density values are used to determine the correct ink key
settings as described herein, where the reference markers are
compared to a target (desired) ink density, which target ink
density is either provided by pre-press information, manually set
by the operator, or otherwise determined, to set overall ink
saturation levels for the entire substrate across one or more ink
zones, as well as comparing the ink density of the reference
markers to each other to maintain ink density equilibrium and,
accordingly, neutral tone. Illustrated in FIG. 12B is a schematic
representation of a position marker in between primary and
secondary reference markers. Illustrated in FIG. 13 is a schematic
representation of reference markers in relation to a substrate,
having one pair of reference markers within each ink zone.
Illustrated in FIG. 7 is a schematic representation of a color bar,
wherein a single color bar has a plurality of color patches. The
associated artwork for the color patches/color bars is provided by
the present UCC program. In color bar mode, color bars are printed
on each image produced by the printing press in order to obtain
representative samples of target color from each print unit. A
color bar pattern typically, but not necessarily, repeats for each
ink key in the print fountain. These patches are scanned by the
imaging assembly and the resulting color values are used to
determine the correct ink key settings.
Using one of the consoles of the invention, a press operator sets
up following job specific details: 1. Color printed by each
fountain in a system. 2. Ink Fountain to surface relation. 3. Color
of a color bar master patch (in a CCC process, as per commonly
owned U.S. Pat. No. 7,187,472). 4. If the job uses color bar or the
job would run in gray spot mode. 5. Location of color bar or
reference markers from leading edge of the print. 6. Starting and
ending ink zone location for imaging assembly scanning. 7. Location
for multiple regions of interest (X and Y coordinates) for each
surface in the system. 8. If the job uses a color bar, the
configuration specifying following details for each patch in ink
zone in the system: (a) Color of each patch
(Cyan/Magenta/Yellow/Black/Special color) (b) Type of patch
(Solid/50% density/75% density/clear/trap/etc.) 9. The target color
values (target density; known from pre-press information) for each
color to be printed on the substrate (Note, the operator may also
override the color neutrality and add a tint to the image by
changing target densities). 10. Type of substrate (paper) to be
printed upon (coated/newsprint/etc.) 11. CIP3 or other file type
available from pre-press software to provide coverage data for each
color being printed on each surface of the substrate. This
information is used to determine initial ink key preset and ink
stroke preset. This information may also be obtained by separately
scanning the substrate to determine target color values. This
determines the initial starting point, or preset, for the ink keys,
and is done regardless of how ink density data is collected during
a printing run.
Job files are preferably edited locally on the user console and
therefore can be created or changed independently of the job
running on the engine. As used herein, the term "job file" is used
to describe a memory. After editing, all job files are preferably
saved on a central file server memory which may be physically
co-located with the engine or console, or which may exist
independently on the network. When the operator is ready to run a
job, he selects from the list of stored jobs and touches the RUN
button on touch screen. Preset values of ink keys, ink stroke and
water are communicated to the print unit controllers which in turn
set up the printing press. The engine also preferably polls each
PUC periodically to confirm that communication link is alive and
also to read back positions of controlled ink keys, ink stroke and
water settings, PUC status and alerts. The communication protocol
between the engine and PUC depends on the specific requirements of
different makes of PUCs.
The operator can place one or multiple surfaces in AUTO mode. There
are three different startup options for the AUTO mode: Ideal,
Current and Last Used. "Ideal mode" brings all ink color values to
those defined in the job file. "Current mode" reads the ink color
values presently being printed and maintains these values or holds
the color wherever the operator has manually set it. "Last mode"
simply resumes with the previously used settings, assigning the
color values which were used when this job was running last in AUTO
mode. Preferably, the engine automatically saves all job settings
and ink color values. When the operator starts printing on the
press, the UCC apparatus gets a press printing signal from press.
After a user defined delay (set by changing parameters) which
allows the printed image to stabilize, the UCC engine sends
commands to each imaging assembly motor to position the imaging
assembly at a specific location. UCC also polls these motors to
confirm that the required move is accomplished. The corresponding
strobe board processes the trigger signal and image acquisition is
initiated through the camera driver software. The acquired image is
preferably stored in the random access memory (RAM) of the engine.
Further processing of the acquired image, see FIG. 11, is performed
based on the "color bar mode", see FIG. 2, or "gray spot mode" of
job operation.
In the color bar mode, the UCC apparatus loads a count
corresponding to the color bar location into the counter board and
commands the counter board to start trigger pulses for image
acquisition. Image analysis is performed to identify the color bar
in the acquired image. If a color bar is not found in the acquired
image, the engine changes the count in the counter board to advance
or retard the area of the printed image visible to the imaging
assembly. The search distance along the Y axis of the substrate is
programmable with engine parameters. When a valid color bar is
found in an acquired image, its location is stored for use. Next, a
master color patch is preferably identified in the color bar and
its location is saved. A master patch is a visually distinct color
patch within a color bar that is typically printed in the center of
the group of patches associated with a particular ink zone. Whereas
the typical color patch is a simple rectangle, the master patch's
corners are missing in distinct and unique patterns. These patterns
form a 4 bit binary encoded value which increments and repeats in a
predetermined fashion across the substrate in successive ink zones.
The binary code is derived by assigning a place value to each
missing corner of the rectangle, allowing 15 unique codes. The 16th
code is zero, which is a simple rectangle. The system uses the
presence of this binary coded master patch as a confirmation check,
along with its color, that the patches are correctly centered in an
ink zone. Further, the sequence of the binary codes ensures that
the particular group of patches is aligned with the correct ink
zone, and not its neighbor. This corrects problems on the printing
press caused by lateral movement of the substrate and also
deliberate offsets introduced by the press operators to align
substrate to various operations on the press unrelated to the
UCC.
Once the master patch is located, the imaging assembly is then
preferably moved such that the master patch moves to a specific
location in the field of view. This operation aligns the imaging
assembly to the patch group from a specific ink zone. Next, the
imaging assembly is preferably moved along the X axis (in a
direction perpendicular to the moving substrate) by one ink zone at
a time until the color bar patches disappear. The last location
where a valid color bar was found becomes one extreme of the
scanned area of the substrate. The opposite end of the substrate
along the X axis becomes the other extreme of the scanned area of
the substrate. Once these extremes are located and stored,
sequential scanning of all of the ink zones commences.
In the color bar mode, color bar location, type and size of the
patches are very important factors in accurate and efficient color
measurement. It is important for the computer engine to be able to
quickly and accurately locate the position of each patch on the
color bar from the image provided by the camera. The color bar
should be distinguished from the surrounding printed material. Some
existing equipment requires that a white border of some
predetermined minimum width must surround the color bar. Others use
unique geometric shapes or cutouts embedded within the color bar.
The recognition algorithm according to the present invention allows
the color bar patches to be simple rectangles of any size or
proportion specified in advance. Additionally, the surrounding
printed material is irrelevant to the recognition of the color bars
and may therefore directly adjoin them with no bordering area, i.e.
"full bleed".
FIG. 2 is a flowchart representing a recognition algorithm showing
the steps for recognizing color bars and color patches. The
recognition algorithm assumes the color bar runs horizontally along
the width of the substrate. Each patch is the same size and shape
as specified in advance. All of the patches for a given key fall
into the field of view of the camera at one time, and no two
adjacent patches are the same color. Typical size of a color patch
is 2 mm along the Y axis and 3.5 mm along the X axis with a 0.5 mm
space between adjacent patches.
Color patches in the color bar can be of the solid, n % screened
(e.g. 25%, 50%, 75%), clear and one color trapped under another
types. The solid patch is normally used for measuring solid ink
density. A 50% screened patch is normally used for measuring dot
gain. A 75% screened patch is normally used for measuring contrast.
A clear patch is used for calculating the unprinted substrate color
value. A trap patch is normally used to measure the trap value of
one color printed over the other. A three color overprinted patch
can be used to measure gray balance, similar to the alternate "gray
spot mode" of the invention.
The patches on the color bar can be easily recognized in the
acquired image by "edge detection" and "blob analysis" techniques
that are well known in the image processing industry. Although the
vertical location of the color bar (circumferential relative to the
print cylinder) within the printed image is known in advance,
differences in substrate tension, and the location of the imaging
assembly relative to the position encoder require that a search be
conducted to find and center the color bar. In normal operation, an
area of +/-four inches from the expected position is searched along
the Y-axis (vertically) with the imaging assembly placed in the
expected center of the page horizontally. On cue from the counter
board, the strobes are triggered for an interval short enough to
freeze the image from the passing substrate and long enough to
properly saturate the imager with color information. This image is
analyzed to determine if any patches are present and qualified in
shape, size and quantity. If they are not, a new vertical position,
approximately 1/3 of the field of view removed from the first, is
computed and another image is taken. This continues through the
scan range until a qualified color bar is found or until the
operator aborts the search. Since substrate width can change from
job to job, UCC also finds the physical end of the color bars to
decide the range of ink zones to be scanned for the job.
Color bars are printed on each image produced by the printing press
in order to obtain representative samples of target color from each
print unit for each individual color, i.e. cyan, magenta, yellow or
black without any other color component. This color bar pattern
repeats along the X axis for each ink key in the print fountain.
These samples are scanned by the camera and the resulting color
values are used to determine the correct ink key settings. As
discussed above, it is important for the computer to be able to
quickly and accurately locate the position of each sample, or
"patch", on the color bar from the image provided by the
camera.
Once found, the color bar patches are examined for their color
values, beginning in a first ink zone and then sequentially through
one or more additional ink zones. In each ink zone, the imaging
assembly is moved to center the master patch in the field of view.
The difference between the actual X and Y location of these patches
and the operator programmed location is calculated and used as
offsets to align the imaging assembly to the printed information. A
previously defined master color patch is identified and its
position within the field of view is determined. The imaging
assembly is moved horizontally, and the encoder counter board is
reprogrammed, to position the master color patch in its correct
position within the field of view. The remaining color bar patches
are then examined for the correct order. If this final test is
passed, the color bar is fully identified. The final position
computed for the imaging assembly is then used as a reference for
positioning it to image the color bar for any key or any random
region of interest on the printed substrate.
The camera next scans the image one ink key width at a time in each
direction horizontally until qualified color bars are no longer
found. This is used to define the edges of the printed page, and
therefore the area to be scanned for color control. For each color
bar image acquired subsequently during the scanning process the
imaging assembly's reference point is continually "fine tuned" to
compensate for variations in the substrate's path through the
press. This fine tuning process uses the master patch and color
order in the same manner described above.
A special case for calibration is provided for both color bar mode
and gray spot mode, where the entire vertical range is searched,
and the resulting position is used to establish a "zero reference"
or "encoder zero point" for a particular press configuration.
Normally this is done when the system is installed, and the
established zero reference is stored and used as the start point
for all subsequent normal scans, thus speeding the search process
considerably. This procedure may be repeated if the timing between
the print cylinder and encoder are disturbed for any reason, such
as for maintenance.
Whether in color bar mode or gray spot mode, images from the
imaging assembly are digitized as "pixels", or points of light of
various intensity and color, and these pixels are analyzed for
determining color value. Each pixel is composed of a mix of three
primary colors, red, green and blue. When mixed virtually any
visible color may be produced. Each primary color has 256 possible
intensity values; therefore 16,777,216 possible distinct colors may
exist. Gray pixels run the range from pure black through pure white
and occur where approximately equal amounts of ink are overlapping
on the substrate. Because of variation in color register, ink
pigments and lighting, plus various electronic distortions and
noise, a color area will not always produce the exact same unique
color value. The unique method of the invention described herein
and including the UCC computer program which is incorporated herein
by reference, distinguishes colors to correctly identify each color
patch or reference marker as unique to itself and yet different
from the background image.
In either the color bar mode or the gray spot mode, the pixels for
each camera acquired image are arranged in the memory of the
computer as repeating numerical values of red, green and blue in
successive memory locations. The acquired image is made of X pixels
wide by Y pixels high, and the numeric representation of the pixels
repeats regularly through the computer memory thereby creating a
representation of the visual image which may be processed
mathematically. The exact memory location of any pixel is located
by multiplying its Y coordinate by the number of pixels in each
horizontal row and again by three, then adding its X coordinate
multiplied by 3. For example, if the image is 640 pixels wide (X)
and 480 pixels high (Y), and one needs to know the location (M) for
the numerical value of the pixel located at 30 (Xv) by 20 (Yv), the
formula would be: M=(3.times.)(Yv)+3Xv, M=38,490 for red, 38,491
for green, and 38,492 for blue.
Using this formulation each image of 640.times.480 pixels requires
921,600 numeric values for a complete representation. The color bar
recognition algorithm uses this formula repeatedly to locate pixel
values to compare and ultimately determine the X and Y coordinates
of each patch in the color bar. The same recognition algorithm
similarly locates pixel values for the primary and secondary
reference markers, and these steps are described in further detail
in commonly owned U.S. Pat. No. 7,187,472.
In the color bar mode, a sub area of the color patch may be
considered rather than the entire color patch. The size of the sub
area of the patch is determined by the parameters. The average RGB
value of the pixels in the sub-area is considered in determining
the color value of the patch. For example, for a patch size of 70
pixels.times.30 pixels, a sub area of 55 pixels.times.20 pixels in
the center of the patch may be considered for determining the
average color value of the patch. This prevents color errors from
occurring due to camera artifacts and motion distortion.
Accordingly, each patch in a ink zone is typically identified for
its color by considering an inspection area smaller than, and
contained within, the color patch. Average of all the pixels in
this area is calculated for red, green and blue channels. In both
the color bar mode and the gray spot mode color correction and
conversion from "rgb" to "cmyk" is applied according to the
following matrix equation:
.times.
.function..function..function..function..function..function..func-
tion..function..function.
.function..function..function..function..function..function..function..fu-
nction..function..times..times..function..function..function.
##EQU00001## where c, m, y, and k (cyan, magenta, yellow and
black/gray) represent the primary colors used in printed media, and
where r, g and b (red, green and blue) are camera generated color
values and represent the primary colors used to represent images
within computer media, and the remaining terms represent conversion
constants.
Constants in the matrix equation are derived during the calibration
process. These constants can change based on changes in color
values of standard inks used in a process. Based on corrected r, g
and b values for each patch or reference marker, color values (ink
densities) are determined based on a empirical data generated using
industry standard logarithmic formulas to convert from transformed
color values to actual ink density values. These values are
compared against target color values for that specific ink zone. If
the difference between these two values is outside acceptable
limits, a new ink key position is calculated for the ink unit
printing that color and the engine communicates this new position
to the corresponding PUC.
The imaging assemblies also scan in both directions along the X
axis, being moved by the linear drive. The imaging assemblies
continue scanning the color bar or reference markers until the
press stops printing or the operator changes the mode of a surface
from AUTO to MANUAL. The imaging assembly continuously monitors the
position of the color bar or reference markers/reference marker
pairs and adjusts the Y axis position to keep color bar/reference
marker pairs centered in the camera field of view. Any substrate
movement along the X axis is also corrected by the engine by
keeping track of master color patch/reference marker location
within the field of view. If an imaging assembly loses
synchronization with the color bar/reference markers for any
reason, the color bar/reference marker pair searching procedure is
reinitiated.
If the job is configured for gray spot mode, the first task once
again is to analyze the image from pre-press information to find
the coverage of different colors in different ink zones and preset
the ink fountain key openings to get the printed substrate close to
the required colors. Ink key opening presets are just an
approximation and may not be a perfect setting. The second task is
to analyze the color information scanned from the substrate being
printed on the press, compare it with the desired color values and
make corrections to the ink key openings to achieve the desired
color values, i.e. ink density values of each ink in each ink zone.
The third task is to continuously analyze the printed substrate and
maintain color values of one or more colored image portions
throughout the job run length.
In gray spot mode, this third task is accomplished by continuously
measuring/analyzing, comparing and controlling the ink density
values of one or more pairs of reference markers printed on the
planar substrate in each ink zone, which reference markers are
positioned adjacent to said one or more colored image portions. In
this embodiment, pairs of reference markers are printed on each
image produced by the printing press in a pattern that repeats
along the lateral axis for each ink key in the print fountain,
similar to the printing of color bars described previously. These
samples are scanned by the camera and the resulting ink density
values are used to determine gray balance and the correct ink key
settings therefrom, where the secondary reference marker is
processed once for each color present to obtain the density
contribution of each primary color component. For example, a
three-color reference marker is processed three times to obtain the
ink density contribution of each primary color.
As illustrated in FIG. 12A and FIG. 12B, each pair of reference
markers comprises a primary reference marker and a secondary
reference marker. The primary reference marker comprises black ink,
is preferably a halftone, more preferably is a halftone having
coverage of greater than 0% but less than 100% (solid), and is most
preferably a 50% halftone printed with black ink only. The
secondary reference marker comprises one or more of cyan, magenta
and yellow ink components, preferably comprising all three of cyan,
magenta and yellow inks. However, it should be understood that, the
same logic used for these four primary process colors (cyan,
magenta, yellow and black) can also be applied to a mixed color of
known color values. Each of said primary reference marker and said
secondary reference marker has an ink density value, wherein said
black, cyan, magenta and yellow inks each have an individual ink
density value, and wherein the ink density value of the secondary
reference marker equals the combined individual ink density values
of the one or more cyan, magenta and yellow inks. Individual ink
density measurements are derived according to the methods discussed
in commonly owned U.S. Pat. Nos. 7,187,472 and 7,477,420, the
teachings of which are described in detail herein. The steps for
achieving color value/ink density determination in an acquired
frame image are summarized in FIGS. 12 and 13.
When the colors of the two reference markers are in balance, both
dots will produce identical values for reflected ink density, and
such is preferred. Further, when all three of the primary colors
cyan, magenta and yellow are present in the secondary reference
marker and the individual ink densities of said primary colors are
all equal, the secondary reference marker will appear as neutral
gray in color. If only one or two of said primary colors are
present, or if all three are present but their individual ink
densities are not equal, then the secondary reference marker may
not appear as a neutral gray. For example, if fewer than all three
primary colors are used for the secondary reference marker its
color will not be a neutral gray, but rather a tint.
The system of the invention allows for tint correction by changing
(increasing or decreasing) the individual ink density, or "target
density", for a specific primary color. The contributing individual
ink densities may still be derived for these tints but the target
density values will be unknown without experimentation or previous
measurement by the operator, rather than being known already from
pre-press information. Once these individual target densities are
determined, automated control may proceed as outlined.
Specifically, ink film thickness, controlled via conventional ink
fountain keys, is adjusted to achieve the desired color. Overall
color saturation may be adjusted by changing the black ink density,
and compensating the other colors in proportion to maintain the
reasonable match.
Each of the reference markers in each reference marker pair may be
circular or another shape, with a nominal 1.5 mm (.about.0.06'')
diameter. Reference markers smaller and larger than 1.5 mm may also
be used for the process control, but approximately 1.5 mm is most
preferred. Circular reference markers are also most preferred
because they do not tend to draw the eye to themselves, and obscure
and unobtrusive gray dots that do not attract the eye are desired.
Square, rectangular or triangular reference markers are more
apparent and therefore less desirable, but they will work to
control the color with no difference compared to round markers. The
reference markers are differentiated from other random print on the
page by their geometry and spatial orientation. As illustrated in
FIG. 13, one pair of reference markers are preferably located in
each ink zone and the reference markers preferably lie along an
approximate straight line running perpendicular to the direction of
motion of the substrate, and are preferably a specific distance
from one another along said line. It is also preferred that the
reference markers are printed on a contrasting monotone background,
preferably with no other print in-between the markers. It is also
preferred that color to color registration be of such quality as to
eliminate color fringing and shape distortion. Detection of color
fringes around the edges of the reference markers will preferably
immediately halt processing and control of the reference markers.
For example, the system is looking for monotone markers, and out of
register conditions will distort the shape of the marker. If it is
distorted and monotone area of the correct shape and size is not
recognized, no marker will be found. When more than a given
percentage of markers are not recognized, the system assumes that
there is a problem and the system automatically reverts to the
manual mode where printing will continue but the color adjustment
process is halted.
As discussed above with regard to the color bars, it is important
for the computer to be able to quickly and accurately locate the
position of each reference marker in a reference marker pair from
the image provided by the camera. This includes the ability to
recognize and adjust for any physical movement of the substrate
during the printing operation. Accordingly, similar to the odd
shaped master patch used in conjunction with color bars in color
bar mode, camera position in gray spot mode may be verified by a
unique geometric shape located in the otherwise blank space
in-between or relative to the primary reference marker and
secondary reference marker. In gray spot mode, these unique
geometric shapes are referred to herein as "position markers". The
shape of the position markers should be different than the shapes
of the primary and secondary reference markers, and should be
positioned at a known distance from each of the primary and
secondary reference markers. As illustrated in FIG. 12B, a
preferred position marker comprises a thin vertical line, because a
thin line would be unobtrusive, which is desirable for the reasons
previously stated. Preferably, this thin vertical line is centered
between and equidistant from each of the primary reference marker
and secondary reference marker in one or more of said reference
marker pairs. Additionally, although thin vertical lines are
preferred for said position markers, other shapes would work
sufficiently as well. Position markers may also be used in one or
more locations across the substrate.
In the gray spot mode, the position marker is used in the manner as
the master patch in the color bar mode to verify the lateral
position of the primary reference marker and/or the secondary
reference marker on the substrate relative to the position/location
of the position marker. As the camera scans the ink zones across
the substrate, it verifies that position markers exist in the
correct places and any offset in the physical position of the
substrate locator mark is noted. These offsets are considered for
accurately positioning the imaging assembly to keep alignment
between the imaging assembly position and printed area
corresponding to the ink zones. This may be performed on a regular
basis to ascertain the alignment between the imaging assembly
position and printed area corresponding to the ink zones to
maintain image synchronization. If the markers are not in the
expected locations, no processing will occur to prevent incorrect
color adjustment, and the system will go back into the search mode
to verify that it is scanning the correct markers.
Scanning and/or color adjustment of the reference markers may be
halted if it is recognized that the reference markers are out of
registration, if position markers are in unexpected positions, or
if position markers are missing where they are expected. More than
a predetermined number of these errors will preferably immediately
halt processing and control. Pantone Matching System (PMS) or other
non-process (non-primary) colors are generally not controlled
automatically in this mode. However, they may be printed on the
page under manual operator control, but must not be included in any
of the defined reference or position markers.
As stated above, the user interface allows the operator to select
three different startup modes: "Ideal", "Current" or "Last Used".
The operator may also override the settings across the page, or in
zones as small as a single ink zone. Individual color ink density
target values may be changed to effect the overall tint of the
image, and all density targets may be moved together to effect the
overall color saturation. The operator may also assign primary
colors to various printing units to suit the needs of the press and
the job. The invention also includes a special "Follow Black" mode
that allows the ink density targets for all contributing primary
colors to proportionately follow the black ink density target.
Compensation is also available for various paper types. Since
different papers absorb inks differently, a library of paper types
is kept on the controlling computer. This is important because
paper types define 1) the target densities for each contributing
primary color in an image; 2) the overall reaction of the system to
color variation to allow smooth overall control of the printing
process; and 3) the native tint of the blank paper.
Regardless of the mode selected, when changing ink key positions on
the printing press there is typically a delay from the time a
change in ink key position is initiated to the time the full effect
of that change shows up on the substrate. Typical delays on a web
offset printing press can be 500 impressions, where one impression
is equal to one rotation of the printing cylinder. In the preferred
embodiment of the invention, when the engine makes a change in a
specific ink key position, it will wait for this delay to expire,
and then further wait until the measured color stabilizes before
making further changes to that specific key.
Further, if the press speed drops below a specified speed, as
defined by a parameter typically set during installation, the
imaging assemblies stop scanning and they are parked to one of the
extremes along X axis. If the engine is in AUTO mode, scanning and
key movements will resume after the appropriate delays once the
press speed is restored to normal.
When an imaging assembly is scanning a specific surface, the
operator can preferably touch a VIEW key on the console touch
screen to see the acquired image on the console monitor. In this
mode, images are updated as the imaging assembly scans across the
substrate along the X axis. The operator can preferably request an
image of a specific ink zone by touching the appropriate buttons on
the touch screen. The operator can also request the image of a
specific region of interest (ROI) specified by the operator as X
and Y coordinates on the substrate. Any number of ROI areas may be
specified during the job setup or during the run in AUTO mode. When
a specific image is requested, following actions take place: 1.
Sequential scanning of keys on the corresponding assembly is
temporarily halted. 2. The corresponding imaging assembly is
positioned to the X (lateral) location of required image. 3. The
encoder count number corresponding to the Y (circumferential)
location of the required image is loaded in the counter board. 4.
An image is acquired and stored in the engine for further
processing. 5. The image is passed to the console and displayed on
the screen. 6. Normal key scanning resumes where it left off.
At this point, the operator can touch anywhere on the displayed
image. UCC then calculates the average density of all the pixels
within the specified area and displays it on the screen. ROI
dimensions can also be changed by changing motorized zoom and focus
in the camera.
UCC is built with statistical quality monitoring (SQM) features.
Color value data (ink density data) is stored at the end of each
pass across the width of the substrate in various industry standard
formats. This data is displayed on the screen, preferably in the
form of a graph. This data is also preferably available on the
Ethernet network and the customer can import this data directly
into commercially available statistical quality control, database
or other software of their choice.
Other maintenance functions are also preferably provided to save
the current position of all keys on all ink fountains in the
system, and open or close ink fountains to a predetermined value.
When normal operation is resumed, the keys on these fountains would
return to the last saved values.
Changing the encoder belt is a maintenance procedure which may
disturb the encoder timing in relation to the print cylinder.
Accordingly, UCC has an encoder teach mode feature. When this
feature is activated for a specific surface, the present UCC system
searches for the color bar/reference marker pairs within the entire
possible Y axis positions. When a color bar/reference marker pair
is found, the offset from encoder index pulse is calculated and
saved.
Due to the aforementioned disadvantages of color bars, if a color
bar is necessary, it is desirable to have the smallest possible
color bars. During the start of the printing process, two factors
affect the print quality the most--register and color. It is also
well known that most automatic register control systems cannot
identify register marks unless the color for the marks is correct
and the print is clear. One preferred automatic register control
system that can properly identify such register marks described in
commonly owned U.S. Pat. No. 6,621,585, the disclosure of which is
incorporated herein by reference. Most color controls have problems
recognizing color bars due to register error between colors.
Automatic register control and color control work sequentially
instead of working in parallel. In such cases, performance of one
affects the performance of the other. The overall effect of this
interdependence is increased waste.
The color register control of the invention is based on shape
recognition, so it is very tolerant to the print quality and color
of the printed register marks. A color bar recognition algorithm is
provided that is very tolerant to color register error. Operating
in the gray spot, UCC does not need a color bar. The combination of
these technologies provides the best performance since both
controls work in parallel.
As explained previously, the image available from pre-press is
analyzed during job setup. Typical information available from
pre-press in CIP3 format is arranged in layers of different color
separations, each layer representing one printed color. A
combination of all color separation layers makes the complete image
being printed on the press. Each color separation layer is divided
into ink zones that are aligned with the ink keys on the printing
press, such that the width of the ink zone is equal to the width of
ink key and the length of each ink zone is equal to the
circumference of the printing cylinder. This information is used to
calculate the initial key settings for each ink zone for each color
being printed.
The size of the image acquired by imaging assembly is typically
2.00'' wide.times.1.50'' high. Color densities are calculated for
each color in each reference marker or color patch as the imaging
assembly continuously scans the markers/patches to determine actual
color values. At the end of each pass, the color densities are
updated and any differences between the target and actual color
density are calculated. Based on these differences, ink keys in
corresponding zones are opened or closed to maintain constant
color.
The invention can be further understood through FIGS. 1-13 of the
invention which are described in detail as follows:
Looking to the figures, FIG. 1 provides a system overview of the
invention. The system preferably comprises an engine 100. The
preferred engine functions include communications 102, press
control 104 and image analysis 106. The communications 102 function
takes care of the communications between the engine and all
peripherals attached to the engine. The press control 104 function
provides control signals for moving the ink adjusting mechanism on
the press. The image analysis 106 function analyzes the image
acquired from the imaging assembly 116. Three modes of
communication are provided for the engine to communicate with
various peripherals attached to the engine. An industry standard
Ethernet backbone network 128 is provided to communicate with a
pre-press server 130, a system management and statistical reporting
workstation 132, printers 134 and single or multiple user consoles
136, 138. An industry standard IEEE 1394 bus 124 is provided to
communicate with one or more digital color cameras 122, to pass
instructions to the camera(s) and also to acquire image information
from the camera(s).
One imaging assembly 116 is provided for each surface of substrate.
An imaging assembly comprises a positioning motor 118, 620, see
also FIG. 6, for positioning the assembly across substrate 650.
Each imaging assembly also comprises a digital color camera 122 and
a strobe assembly 120. The strobe illuminates the field of view for
a very short period of time and the image is acquired by the
camera. Strobe illumination is synchronized with the position of
camera in relation to the substrate by an input trigger signal from
an encoder and counter board 126. The same trigger signal is also
transmitted to the camera to synchronize image acquisition with
strobe illumination. One encoder 126 per substrate is provided to
get the position information for timing the image acquisition with
the printed substrate.
The network backbone 140 provides communication between the engine
and one or more print unit controllers 108 and also between the
engine and the imaging assembly 116. One Print Unit controller 108
is preferably provided per printing unit on the printing press. The
print unit controller 108 preferably provides functions for key
control 110, ink stroke control 112, and water control 114, and one
print unit controller may control one or more sets of ink fountain,
ink stroke control and water control. Depending on the printing
process and printing press design, ink stroke control 112 and water
control 114 may or may not be built into the system. Since print
unit controller architecture changes between different presses and
press manufacturers, the communications between the engine and the
PUC may be performed using other industry standard backbones like,
Ethernet, Arcnet, Profibus, RS232, RS485, etc., as required.
FIG. 2 gives details about color bar recognition process 200. When
UCC is used in a "color bar mode", this process is used to identify
color bar and color patches corresponding to each ink zone on the
substrate. The process is also used when the operator programs UCC
system for a "gray spot mode" and when UCC gets press interface
signals to start the process. An image is acquired 202 according to
the process explained in FIG. 11, beginning with a first ink zone
and then proceeding sequentially. The image information thus
acquired is transmitted to the UCC computer. This stored image is
digitized as pixels.
The image thus acquired is further analyzed for each row 206 and
each column 208. Areas of a single color are marked as possible
patch locations. For each possible location of a color patch, the
top and bottom vertical edges are found 210. If the distance
between the top and the bottom edge meets the patch size criteria
212, then precise top, bottom, left and right edges for the patch
are found 214. From this information, precise size of the patch is
determined. Edge detection algorithms are well known in the image
processing industry. If this size meets the patch size criteria
218, this can be a potential patch along the color bar and its
location and color information is stored for future use 220. This
process is repeated to find all potential patches in the acquired
image.
When all potential patches are identified in the image, first they
are sorted and merged to eliminate duplicate potential patches 222.
Then, the highest concentration of patches along the X direction
are found from these patches and all others are rejected 224. Based
on the location and size of these patches, any missing patches are
interpolated and extrapolated 226. Next, the binary code of the
master patch is identified and compared with the location
corresponding to this ink zone 228. Also, the color of each patch
is identified and compared with the color order configuration set
by the press operator during job defining process. At the end of
this process 230, the information in the acquired image for each
color patch along the color bar is available for further color
analysis.
FIG. 3 gives further details about a print unit controller 108. It
comprises a micro controller 300 for logic control. A RAM battery
backup 302 is provided to save memory value in case of power loss.
A hardware watchdog timer 304 is provided to continuously monitor
for reliable operation of print unit controller operation. RS-485
unit control network 306 hardware is provided to communicate with a
RS-485 network backbone 312, 140. Additional hardware is provided
for an RS-232 local monitoring and programming port 308. Unit
address and function select 310 hardware is provided to
individually address each print unit controller. Each print unit
controller can control two ink fountains on a printing press. Upper
fountain control buss 314 and lower fountain control buss 324 are
connected to the micro controller 300. The micro controller is also
attached to ink stroke 318 and water 320 Input/Output hardware
equipped for either analog or digital signal input/output
interfacing. General purpose inputs and outputs 322 are provided
for interfacing with various other events and functions on a
printing press. A local analog multiplexer 316 is provided for
reading analog signals from various inputs on the processor
board.
FIG. 4 gives further details about upper/lower fountain control
buss 314, 400 operation for a fountain key adapter. Each fountain
key adapter can adjust the position of a plurality of ink key
actuators and it can also read the position for the corresponding
ink keys. An address select 402 switch is provided to cascade
fountain key adapters to provide control for a plurality of ink
keys. Steering control logic 404 selects operation on the top or
the bottom fountain. Output drivers 406 switches ink key actuators
408, 410, 412 power to open or close the ink key. Analog
multiplexer 414 reads the ink key 416, 418, 420 positions.
FIG. 5 provides details about strobe operations. Power is supplied
to the strobe assembly through a power regulator 500. A trigger
input to the circuit is used to synchronize strobe illumination
with image acquisition. The strobe illuminates for a fixed time
synchronous to the trigger input pulse. Timing control 502 provides
the logic for timing between trigger input and illumination. One or
more LED arrays 506, 508, 510 can be attached to the LED power
driver assembly 512. Each LED array can have one or more LEDs for
illumination. Timing control 502 also interfaces with camera
trigger control 504. Camera trigger control processes the timing
signal from timing control and provides a camera trigger signal
appropriate for triggering the camera for image acquisition.
FIG. 6A illustrates the apparatus for systematically scanning the
image from the substrate 650. It is composed of two frames 600. A
web lead-in roller 602 is provided to accept the substrate 650 from
previous process equipment. A web lead-out roller 604 is provided
to deliver the substrate to the next process equipment on the
printing line. Between lead-in and lead-out rollers, the substrate
travels over two rollers 606, 608. The imaging assembly comprising
a color camera and a strobe light 610 scans the top side of the
substrate passing over the roller 606. The imaging assembly
comprises a color camera and a strobe light 612 scans the bottom
side of the substrate passing under roller 608. Both imaging
assemblies 610, 612 are mounted on a carriage 614, which moves and
positions the imaging assembly to operator specified locations
across the substrate width. The carriage 614 is equipped with
v-groove guide wheels and the guide wheels keep the camera on the
guide 616. The carriage is also equipped with a linear drive in the
form of motor 620 and a timing belt pulley installed on the shaft
of the motor. A timing belt 618 is provided across the width of the
carriage guide. Rotation of the motor 620 on the belt moves the
carriage 614, motor 620 and imaging assembly 612, 614 across the
substrate. The carriage guide is mounted on the mounting brackets
622, which are subsequently mounted on the frames 600. FIG. 6B
presents a side view of the equipment described above.
FIG. 7 provides details about the color bar configuration. The
color bar consists of color patches arranged in a row along the X
direction of the substrate, from one end to the other end. The
space on the color bar corresponding to each ink zone can have up
to 8 color patches. Each patch can be printed with a solid color, a
% tint of a color, a white space or an overprint of one color on
top of the other color. More patches can be accommodated if the
patches are made smaller or if the patches are stacked in multiple
rows. In order to assure correct alignment of the imaging assembly
to the printed substrate, the color bar area in each ink zone
includes a centrally located master patch. The group of color bars
traversing all of the ink zones across the substrate is frequently
referred to simply as "the color bar".
FIG. 8A is side perspective view of an imaging assembly 610
according to the invention, which is the same as imaging assembly
612 as shown in FIGS. 6A and 6B. It comprises color digital camera
806 and two strobes 812 enclosed in an enclosure 800. The camera
806 is mounted inside enclosure 800 by mounting brackets 808 and
the strobes are mounted inside enclosure 800 by mounting brackets
810. The enclosure has a clear window with a non-reflective coating
804 in front of the camera lens. The strobes illuminate the
substrate 650. Light rays 814 from both strobes originate at the
strobe LEDs and reflect back from the substrate and enter the
camera lens. Each strobe may have a single light source, 820 as
shown in FIG. 8B or an array of light sources 840 as shown in FIG.
8C.
FIG. 9 describes an arrangement where the substrate is stationary
and the imaging assembly 932 is mounted on a carriage with
positioning motor 930. In this embodiment, the linear drive
comprises two portions, one which moves the imaging assembly in the
X axis direction and one which moves the imaging assembly in the Y
axis direction in relation to the plane of substrate 902. The
carriage moves on a rail 926 across the width of substrate 902,
also known as the X axis. A fixed timing belt 922 is anchored to
the supports 924, 918. A rail is also supported on two ends with
supports 924, 918. Supports 918, 924 are mounted on brackets 920,
928 with nuts. The whole subassembly travels along the Y axis on
two screws 914, 916. Both screws are supported on one end with
brackets 934, 936. The other end of both screws is driven by bevel
gear assemblies 908, 910. Bevel gear assemblies 908, 910 are
coupled together with a shaft 912. Both bevel gear assemblies are
driven by a positioning motor 906. An encoder 904 is attached to
the motor shaft to give feedback for the Y axis position of the
imaging assembly. The whole assembly is mounted on a base 900 which
also serves as a support for substrate 902. In this arrangement,
the substrate is held stationary and imaging assembly moves in both
the X and Y orthogonal directions in relation to the plane of
substrate 902.
FIG. 10 illustrates the typical nature and layout of print and ink
zones on the substrate. An image is repeatedly printed on the
substrate 1014, where the print repeat length 1006, 1012 is equal
to the circumference of the printing cylinder. This direction is
generally known as circumferential direction or a Y direction. The
width of the printed substrate 1004, 1010 is generally known as
lateral direction or X direction. In a typical printing press, an
ink fountain provides the ink for printing operation. The ink
fountain has several ink keys across the width of the fountain.
Each ink key can be individually opened or closed to allow more or
less ink in the corresponding longitudinal path of the substrate,
called an ink zone 1008. Ink, from the ink fountain, travels along
the ink train through distributor rollers. Any change in the ink
key setting affects the whole longitudinal path, or ink zone,
aligned with the key. A typical printing press also has oscillator
rollers. In addition to the rotational motion, these oscillator
rollers also have lateral motion moving back and forth. The axial
motion spreads ink along the ink zone to the adjacent ink zones.
The height and width of the acquired image 1000 is shown in the
figure. Although the typical width of the image is 640 pixels and
the height is 480 pixels, a different camera resolution can also be
used for the application. Due to distortion and uneven lighting
along the edges of the acquired image, a sub area of the image 1002
is used for the color analysis. This area is also called the image
aperture. The aperture width reflects the actual width of the ink
key.
FIG. 11 gives details about the image acquisition process in UCC,
1100, for getting color information for each ink zone. This is a
general process and it is used to acquire an image of the substrate
in "color bar mode" as well as in the "gray spot mode". The process
starts by positioning the imaging assembly at a desired location
along the X direction, 1102. This is done by providing commands to
the positioning motor and an integrated controller that keeps
tracks of the imaging assembly position along the X direction. The
location of the first image in Y direction is specified by
calculating the encoder value of the first location and setting
that value into the Counter Board 1104 preset. Now, the camera is
armed 1106 to acquire the image when it receives the next trigger
signal. Hardware in the counter board keeps track of the encoder
shaft location, which is attached to a print cylinder. Thus the
encoder shaft location provides precise timing information about
the printed substrate location in Y direction. When the encoder
count in the counter board matches with the preset count, the
counter board generates a trigger signal 1108. The trigger signal
is processed by the strobe board and it illuminates the LED array
for a very short time 1110. This processed signal is also used to
start image acquisition on the color camera 1112. The image
acquired by the camera is transmitted to the UCC computer and it is
stored for further analysis 1114. Operating in either "color bar
mode" or "gray spot mode", the process is finished for this ink
zone 1118 and the imaging assembly may proceed further to get
information about the next ink zone.
FIGS. 12A and 12B show a schematic representation of the gray spot
configuration. A primary marker 1201 and a secondary marker 1202
are printed in each ink zone across the page laterally. The primary
marker 1201 contains the black ink and the secondary marker 1202
contains the ink from the other printed process colors. In several
locations across the page, the markers preferably include a camera
position marker 1203 which is used to verify the position of the
camera over the printed substrate.
FIG. 13 shows a schematic representation of a substrate 1301
including the locations of the reference markers 1304 across ink
zones 1303. The substrate moves in a direction of travel 1302
through the printing press parallel with the ink zones 1303 and
perpendicular with the reference markers. Each set of reference
markers is contained in its own clear space on the substrate
1301.
While the present invention has been particularly shown and
described with reference to preferred embodiments, it will be
readily appreciated by those of ordinary skill in the art that
various changes and modifications may be made without departing
from the spirit and scope of the invention. It is intended that the
claims be interpreted to cover the disclosed embodiment, those
alternatives which have been discussed above and all equivalents
thereto.
APPENDIX
Computer program listing appendix referenced, included and
incorporated in the present application which is included in a
single compact disk CD-ROM labeled "UNIVERSAL CLOSED LOOP COLOR
CONTROL", which is submitted in duplicate. The file size, creation
date and file name on the compact disk CD-ROM appendix includes the
following 115 files:
TABLE-US-00001 SIZE DATE TIME FILENAME 174,226 Feb. 12, 2010 3:25
PM cccStructures.bas 88,450 Feb. 12, 2010 5:48 PM cccConGlobal.bas
12,282 Oct. 8, 2007 4:26 PM frmAutoLock.frm 10,555 Feb. 16, 2004
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3,134 Apr. 27, 2009 3:39 PM frmCIPerror.frm 2,074 Apr. 27, 2009
3:40 PM frmCIPImage.frm 50,135 Nov. 20, 2009 11:21 AM
frmColorEdit.frm 26,408 Feb. 12, 2009 9:47 AM frmControls.frm 5,892
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frmGraphTypeSelect.frm 26,102 Oct. 18, 2004 4:59 PM frmHeadPanel
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16, 2004 9:40 AM frmHidden.frm 24,891 Jan. 30, 2008 9:21 AM
frmJobScan.frm 63,628 Dec. 23, 2009 1:52 PM frmKeyboard.frm 95,643
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AM frmLogin.frm 6,041 Jun. 21, 2006 2:59 PM frmMain.frm 63,259 Jan.
26, 2010 2:10 PM frmMainten.frm 4,944 Oct. 26, 2004 5:04 PM
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5, 2010 4:25 PM frmSurfAssign.frm 105,373 Sep. 14, 2006 9:16 AM
frmTarget xxx.frm 126,382 Nov. 20, 2009 11:21 AM frmTarget.frm
85,596 Feb. 16, 2004 8:40 AM frmTargetxxx.frm 4,880 Jun. 10, 2008
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Jul. 19, 2004 2:05 PM frmWarning.frm 10,159 Feb. 16, 2004 9:40 AM
frmYesNo.frm 79,820 Jan. 20, 2009 11:16 PM frmZoom.frm 70,365 Feb.
16, 2004 9:40 AM frmZoomx.frm 12,537 Nov. 22, 2008 12:40 PM
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tcpClient.frm 1,717 Sep. 3, 1999 1:32 PM WinHelp.bas 1,505 Jun. 13,
2005 10:08 AM ArcnetDeclarations.bas 12,425 Jul. 14, 2008 1:31 PM
ArcnetMonitor.frm 131,806 Dec. 11, 2009 4:08 PM Cal.frm 36,544 Dec.
14, 2009 10:02 AM CameraControl.frm 13,713 Dec. 14, 2006 4:08 PM
CameraProps.frm 1,212 Nov. 10, 2004 10:05 AM DebugPic.frm 38,869
Feb. 20, 2007 12:14 PM eltromat Comm.frm 43,339 Jul. 16, 2008 3:49
PM EltromatZircon Comm.frm 202,227 Dec. 30, 2009 2:44 PM
EngCode.bas 9,839 Jun. 10, 2009 12:46 PM EngDeclarations.bas 8,746
Jun. 10, 2008 9:55 AM EngVariables.bas 36,677 Apr. 30, 2008 3:10 PM
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10, 2008 4:56 PM frmArcnetTestMain.frm 2,378 Apr. 7, 2008 2:27 PM
frmDebug.frm 4,712 Dec. 2, 2009 2:41 PM frmExersize.frm 9,058 Sep.
7, 2007 10:20 AM frmLAB.frm 1,460 Nov. 14, 2008 4:41 PM
frmNothing.frm 1,600 Dec. 10, 2008 4:18 PM frmRX.frm 48,201 May 19,
2006 4:04 PM GCX Comm.frm 59,041 Aug. 18, 2009 8:19 AM GMI Comm.frm
48,737 Nov. 9, 2006 3:57 PM KBA Comm.frm 9,714 Jun. 24, 2005 5:05
PM KBA KeyControlCommon.bas 13,691 Dec. 2, 2009 11:27 AM
KeyControlCommon.bas 42,996 Oct. 10, 2008 10:13 AM MM Canbus
Comm.frm 35,915 Sep. 11, 2006 10:48 AM Monigraf Comm.frm 103,065
Dec. 2, 2009 11:27 AM Perretta Comm.frm 56,713 Apr. 24, 2009 4:32
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11,578 Feb. 16, 2004 10:42 AM Recognize.frm 17,093 Feb. 16, 2004
10:41 AM RecognizeStructs.bas 42,981 Feb. 16, 2004 10:42 AM
RS485.frm 64,386 Feb. 5, 2010 11:29 AM Rutherford.frm 477 Apr. 2,
2008 4:08 PM RutherfordDeclares.bas 112,697 Feb. 12, 2010 3:22 PM
StatusForm.frm 35,322 Jun. 26, 2008 1:38 PM T2 Comm.frm 24,095 Dec.
14, 2009 11:27 AM TCP.frm 95,319 Nov. 20, 2008 4:09 PM
TigerComm.frm 2,490 Mar. 19, 2001 5:30 PM 20020drv.h 4,250 Jun. 10,
2005 9:27 AM 20020sys.h 6,846 Jun. 16, 2005 1:46 PM Arcnet.cpp
34,084 Dec. 23, 2009 10:56 AM CameraDLL.cpp 1,819 Aug. 10, 2006
11:12 AM CameraDLL.h 2,489 Jun. 7, 2001 3:39 PM ficamera.h 4,590
Jun. 14, 2001 3:21 PM fiint.h 14,109 Jun. 7, 2002 9:50 AM iidcapi.h
2,337 Aug. 16, 2002 11:34 AM SonyIIDC.h 3,881 Nov. 18, 2002 9:45 AM
sonyiidcdoc.h 1,749 Aug. 16, 2002 11:44 AM SonyIIDCView.h 296 Jun.
13, 2001 4:15 PM StdAfx.cpp 813 Aug. 10, 2006 11:10 AM StdAfx.h
91,058 Jan. 20, 2010 2:44 PM CLCDLL.cpp 887 Jun. 4, 2009 9:44 AM
cicdll.def 8,848 Nov. 29, 2005 2:05 PM cicdll.h 3,491 Jan. 25, 2001
5:21 PM Encdr2.h 8,070 Jan. 25, 2001 5:04 PM Grabber.c 7,733 Jan.
19, 1998 6:32 PM Grabber.h 293 Nov. 27, 2000 1:56 PM StdAfx.cpp
1,054 Nov. 27, 2000 3:34 PM StdAfx.h
* * * * *